This disclosure is related to the field of electrically operated submersible well pumps (ESPs). More specifically, the disclosure relates to structures for ESP systems and methods for deploying, moving and redeploying an ESP through a wellbore tubing.
ESPs are known in the art for lifting liquid in a subsurface wellbore, as examples, in cases where energy in a subsurface reservoir penetrated by the wellbore is insufficient to lift the fluid to the surface, or where liquid produced from the formation such as water increases hydrostatic pressure in the wellbore so as to reduce productivity of the reservoir of desirable fluids such as oil or more particularly gas. The latter use is known as “dewatering.”
ESP systems known in the art may be deployed in the wellbore at the end of a section of conduit called “tubing” or a “velocity string”, which has a nominal diameter smaller than an internal diameter of a pipe or casing permanently emplaced in the wellbore. The casing serves to maintain mechanical integrity of the wellbore and to hydraulically isolate subsurface formations from each other. The tubing may serve the purpose of providing a smaller diameter conduit to increase the velocity of fluid moving to the surface, thus increasing capacity of wellbore fluid to lift higher density fluid components to the surface for a given amount of total energy (i.e., from the reservoir and from a pump if used).
Certain types of electrical cables may make practical the deployment of ESP systems through an emplaced tubing. Such capability may reduce the cost of deploying, servicing and/or replacing an ESP system as compared to those deployed at the end of a tubing.
In some cases it may be desired to be able to move the ESP after initial deployment and/or to repeatably seal the interior of the tubing after such movement without the need to completely remove the ESP system from the wellbore.